SU-E-T-51: Patient Collision Detection in Proton Therapy during Treatment Planning Phase

Abstract

Purpose: Collision detection of the patient with the proton gantry during treatment planning phase can reduce re‐planning effort and patient setup time. The collision detection in proton therapy should account for specific proton gantry design, treatment beam configuration, and patient geometry. Methods: The coordinates of the surface contour of the gantry head were captured from the proton CAD design and reconstructed relative to the isocenter. This reconstruction accounts for patient specific gantry rotation, snout position, collimator rotation and compensator dimensions based on patient's treatment plan. The patient's body contour and couch, captured from the CT structure DICOM file and CAD design, were also reconstructed relative to the isocenter while considering the couch angle from the treatment plan. The ray‐casting algorithm was applied to monitor collisions by determining if any of the patient and couch body points falls into the polygon formed by the proton gantry spatial contour. Results: A software program was developed for patient/couch‐gantry collision detection in proton therapy. We have successfully predicted collisions in real and artificially constructed treatment plan cases. The collision detection program is being clinically validated as an accurate and quick method to predict patient‐gantry collision in proton therapy. Conclusions: An accurate and quick patient‐specific collision detection program for proton therapy can be implemented and applied in treatment planning phase using proton CAD design and patient CTimages.